A particularly useful source of coloring agents for a variety of foods and beverages are the carotenoids. The carotenoids include carotene, lycopene, bixin, zeaxanthin, cryptoxanthin, lutein, canthaxanthin, .beta.-apo-8'-carotenal, .beta.-apo-12'-carotenal and can provide color pigments ranging from yellow to red. An especially important member of the carotenoid class of compounds is .beta.-carotene. .beta.-carotene is not only useful as a colorant (typically yellow, orange and especially red in color) but also provides a valuable source of vitamin A. For this reason, .beta.-carotene is often included in foods and beverages as a colorant, especially where vitamin A fortification is needed or desired.
One particular food system that .beta.-carotene has been included in for both vitamin A fortification and color are dilute juice beverages. Dilute juice beverages often have a cloudy or opaque appearance by incorporating a beverage emulsion. These beverage emulsions can be either flavor emulsions (i.e., provide the beverage with flavor and cloudiness) or cloud emulsions (i.e., provide primarily cloudiness). Both types of beverage emulsions comprise an oil phase that is dispersed in a continuous water phase, i.e., they are "oil-in-water" emulsions. This oil phase is typically uniformly dispersed in the continuous water phase in the form of fine droplets that give the beverage its cloudy or opaque appearance.
Dilute juice beverages that are intended to be stored without refrigeration (e.g., at ambient temperatures), pasteurization or aseptic packing typically need an antimicrobial preservative. Dilute juice beverages, when exposed to food spoilage microorganisms, can provide a hospitable environment for rapid microbial growth. Such exposure can result from accidental contamination of the dilute juice beverage during manufacturing or packaging. Food spoilage microorganisms can then rapidly proliferate by feeding on nutrients provided by various components (e.g., the juice itself) of the dilute juice beverage.
Preservatives, such as sorbates, benzoates, organic acids, and combinations thereof have been used in dilute juice beverages to provide some degree of microbial inhibition. At levels effective to inhibit microbial growth, some of these preservatives can contribute off-flavors to dilute juice beverages. Accordingly, it has been recently suggested to include certain food grade polyphosphates (especially sodium hexametaphosphate) to enhance the potency of these preservatives at lower levels in dilute juice beverages. See U.S. Pat. No. 5,431,940 (Calderas), issued Jul. 11, 1995, which discloses the use of polyphosphates, such as sodium hexametaphosphate, in combination with sorbate preservatives, such as potassium sorbate, in dilute juice beverages having relatively low water hardness.
Adding .beta.-carotene to dilute juice beverages so that it is well dispersed, as well as providing vitamin A activity and desirable color, has been found not to be an easy proposition. The carotenoids, including .beta.-carotene, are relatively insoluble in water and have relatively high melting points. They are also highly sensitive to oxidation, especially in the presence of water. To make it more water-dispersible, .beta.-carotene is often formulated as a water-dispersible beadlet. These beadlets can be made by dissolving .beta.-carotene in a water-miscible organic solvent, mixing the dissolved .beta.-carotene with an aqueous solution of a swellable colloid (typically gelatin), precipitating the .beta.-carotene in a colloidally dispersed form and then drying the colloidal dispersion. See, for example, U.S. Pat. No. 3,316,101 (Borenstein), issued Apr. 25, 1967 and U.S. Pat. No. 4,522,743 (Hom et al), issued Jun. 11, 1985. See also D. Horn, "Preparation and Characterization of Microdisperse Bioavailable Carotenoid Hydrosols," Die Angewandte Makromolekulare Chemie 166/167, (1989), 139-153; H. T. Gordon and J. C. Bauernfeind, "Carotenoids as Food Colorants," CRC Critical Reviews in Food Science and Nutrition, 18, (1982), 59-97; H. Klaui and J. C. Bauernfeind, "Carotenoids as Food Colorants," Carotenoids as Colorants and Vitamin A Precursors, Chapter 2, (1981).
Even when added as a water-dispersible beadlet, it has been found that .beta.-carotene can still be very sensitive to oxidation in dilute juice beverages that contain sodium hexametaphosphate such that vitamin A activity is rapidly lost and color changes over time, especially when the beverage is subjected to light stress. This has particularly been found to happen when the dilute juice beverage is formulated by dispersing the .beta.-carotene beadlets in water, and then blending this dispersion with the other dilute juice beverage ingredients such as sodium hexametaphosphate. The inclusion of antioxidants such as ascorbic acid has been suggested as a way to prevent the oxidation .beta.-carotene. See U.S. Pat. No. 3,886,294 (Emodi et al), issued May 27, 1975 (use of ascorbic acid as antioxidant for carotenoid coloring compositions); and U.S. Pat. No. 5,153,012 (Ohtaka et al), issued Oct. 6, 1992 (use of a mixture of vitamins C, B.sub.2 and E to stabilize .beta.-carotene even under ambient conditions to minimize its loss from the beverage.) However, even when an antioxidant such as ascorbic acid is included, it has still been found that the .beta.-carotene is rapidly oxidized in dilute juice beverages that contain sodium hexametaphosphate such that vitamin A activity is lost and color changes over time.
The concentration of .beta.-carotene in the water-dispersible beadlet has also been found to be important to the oxidative stability of the .beta.-carotene when formulated in dilute juice beverages that contain sodium hexametaphosphate. For example, when the water-dispersible beadlets contain about 10% .beta.-carotene, it has been found that vitamin A activity and color is rapidly lost over time in such dilute juice beverages containing sodium hexametaphosphate. By contrast, when water-dispersible powders containing only about 1% or 2.5% .beta.-carotene are used, vitamin A activity and color is maintained over time in such dilute juice beverages, even when sodium hexametaphosphate is present. Unfortunately, to provide equivalent vitamin A activity and color, significantly more of these 1% or 2.5% .beta.-carotene powders would need to be included in the dilute juice beverage which increases the processing cost, the ingredient cost, and complexity in formulating the beverage. Furthermore, these 1% or 2.5% .beta.-carotene powders are generally not as physically stable (i.e., they cream more readily) compared to the 10% .beta.-carotene beadlets.
Accordingly, it would be desirable to be able to formulate dilute juice beverages that (1) can be formulated with water-dispersible beadlets containing high concentrations of .beta.-carotene; (2) provide adequate vitamin A activity and color over the expected storage and use life of the beverage; (3) allow the use of preservative systems that contain polyphosphates, especially sodium hexametaphosphate.